1. Field of the Invention
This invention relates to a implant plate system, device and locking screw having at least one locking member. The preferred application for the device is in spinal surgery, however, applications in other areas of orthopedic surgery are appropriate.
2. Description of the Related Art
Many types of prosthetic devices have been proposed in the past. For example, U.S. Pat. No. 5,192,327 to Brantigan concerns a surgical prosthetic modular implant used singularly or stacked together to support and fuse together adjacent vertebrae or to totally or partially replace one or more vertebrae in a vertebral column. Other surgical implant devices and methods are shown in U.S. Pat. Nos. 4,488,543; 5,192,327; 5,261,911; 5,549,612; 5,713,899; 5,776,196; 6,136,002; 6,159,245; 6,224,602; 6,258,089; 6,261,586; 6,264,655; 6,306,136; 6,328,738; 6,361,537 and 6,592,586. Some or all of these devices have improved the success rate and have simplified the surgical techniques in inter-body veritable fusion.
U.S. Pat. No. 6,258,089 B1 issued Jul. 10, 2001 to Campbell et al. for an Anterior Cervical Plate And Fixation System discloses an anterior cervical plate is disclosed, along with threaded fasteners for securing the plate to vertebrae or other osseous material. The cervical plate has several pockets or apertures, preferably at least four, to receive a corresponding number of the fasteners. The pockets have spherical surfaces, and the fasteners have heads with similarly sized spherical surfaces, which when engaged permit each of the fasteners to be oriented at a variety of projection angles with respect to the plate. In connection with each pocket, the cervical plate incorporates a fastener retaining feature. The feature can take the form of a cantilevered tab or a beam supported at its opposite ends, in each case plastically deformable between an open position for admitting the fastener and a closed position for preventing retraction.
U.S. Pat. No. 5,549,612 issued Aug. 27, 1996 to Yapp et al. for Osteosynthesis Plate System discloses an osteosynthesis plate system is particularly well adapted to securely fuse adjacent cervical vertebrae. The plates are adapted for mounting upon the anterior or posterior surfaces of the vertebrae. Plates for mounting on the anterior vertebral surfaces have a concave bone contacting surface and a bone screw locking mechanism integral with each screw hole. Moreover, the bone contacting surface of the plate has a plurality of bone penetrating protrusions to more securely affix the plate to bone. Plates for mounting on the posterior vertebral surfaces also have bone penetrating protections on their bone contacting surfaces. Such plates are formed so as to have a curved bone contacting surface that is concave in the transverse axis of the plate and convex in the longitudinal axis of the plate. The screw holes of such plates are constructed so as to guide a bone screw along a desired angle to improve the anchoring of the screws in bone.
U.S. Pat. No. 4,488,543 issued Dec. 18, 1984 to Tornier for Device For Osteosynthesis Of Fractures Of The Extremities Of The Femur discloses a device for osteosynthesis of the fractures of the extremities of the femur comprises a plate in which holes are provided for the passage of screws intended to be inserted into the bone to make the fractured bone and the plate solid. One end of the plate to be applied against one of extremities of the femur is wider than the other end and includes three holes arranged in an isosceles triangle. The median plane of the one end defines a plane which forms, with the plane of the rest of the plate, an obtuse angle of between 160° and 175°.
U.S. Pat. No. 6,361,537 B1 issued Mar. 26, 2002 to Anderson for Surgical Plate With Pawl And Process For Repair Of A Broken Bone discloses a surgical plate and process for preventing screw backout of repaired bones. At least one pawl is provided on a surgical plate adjacent to a screw hole. A screw having a ratchet wheel is inserted through the hole and screwed into the bone. The pawl engages the ratchet wheel to prevent rotational movement of the screw to prevent the screw from backing out. In a preferred embodiment, a pawl plate comprising a base portion is rigidly connected to the surgical plate and a torsion bar is pivotally connected to the base portion. The pawl is positioned at the end of the torsion bar. In the preferred embodiments, several of these special screw holes with pawls, and several screws (each with a ratchet wheel) are used in bone repair.
While the above approaches may have yielded favorable results in certain circumstances, there remains a need for reducing the need for multiple parts or tools and for providing a simpler, more reliable means and system of facilitating prevention of the screws from migrating out of the bone by axial or rotational movement after the plate is fixed thereto.
Among some of the problems associated with the prior art devices is that after the device is inserted into a patient during a surgical procedure, there was a possibility of inadequate fixation of the implant device due to false-locking of fixating screws.
Another problem with the prior art devices is that the implant device and associated bone graft could loosen after the surgical procedure due to undesired back-out of fixating screws.
Moreover, in some of the prior art devices, the fixation screws are locked to the prosthetic device in a multiple-step process, increasing the possibility for user error or false fixation.
Another problem with prior art implant plate systems is that the screws or fasteners which secured the plate had a tendency to withdraw, causing injury to local structures by the screws themselves.
What is needed, therefore, is a system and method, which facilitates overcoming one or more of the aforementioned problems as well as other problems and to provide a device that has unique features that will facilitate reducing the risk associated with neurological surgeries and advance the present state of the art.
Therefore, there is a need for a plate and fixation system in which bone screws or other fasteners are more securely retained and less likely to work loose or migrate, which reduces or eliminates the need for auxiliary components, screws, tools or additional fixtures.